From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark Lord Subject: Re: What's needed for PMP support? Date: Thu, 21 Feb 2008 21:04:45 -0500 Message-ID: <47BE2DBD.9010704@rtr.ca> References: <4730E312.3090900@navy.mil> <4737C16E.3070607@gmail.com> <4738827D.9060405@pobox.com> <4738F935.1000708@gmail.com> <47BC798F.6070900@pobox.com> <47BE17CA.6060406@rtr.ca> <47BE1833.9090501@rtr.ca> <47BE2C0C.3020801@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from rtr.ca ([76.10.145.34]:3025 "EHLO mail.rtr.ca" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758124AbYBVCEq (ORCPT ); Thu, 21 Feb 2008 21:04:46 -0500 In-Reply-To: <47BE2C0C.3020801@gmail.com> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Tejun Heo Cc: IDE/ATA development list , Saeed Bishara Tejun Heo wrote: > Mark Lord wrote: >> Mark Lord wrote: >>> Tejun Heo wrote: >>>>> The following things are needed for a LLD to support PMP. >>>> .. >>>>> I think that's about it. Feel free to ask if something isn't clear. >>> .. >>> >>> I think we need better semantics around sata_scr_{read,write}(), >>> or more specifically >>> These need to be moved into ata_port_operations >>> so that LLDs can wrap them to properly manage >>> the host controller's global link->pmp value. >> .. >> >> Heck, if .dev_select() took a *device* instead of a *port* >> as it's parameter, then I could probably manage it fine in there. > > Heh... I never thought a PMP aware controller would use TF SRST, so what > you want to do is set pmp value in the register and calling > ata_std_softreset(), right? I think the correct thing to do is to > separate out SRST sequence proper from ata_std_softreset() into, say, > ata_sff_SRST() and build custom softreset around it. After all, the > problem here is the reset sequence not the SCR access. .. Actually, I believe the problem *is* the (pmp) SCR access. The same issue will return again when trying to support hotplug, for example. Any SCR access will steal the active pmp on such hosts. I think we really do need to snoop those, somehow. Cheers